thinking is fun

Why is it that, as you progress towards supposedly higher levels in your career, the trainings tend to get more infantile?

When I was just starting out as a programmer, most of the trainings I took were of course purely technical: how to operate a particular database system, how to write software for a particular operating system. The last time I received such a training was long ago, but I remember being generally treated as an adult. The trainer’s communication style would presuppose a certain amount of intelligence and common sense from the students, and we were assumed to be already familiar with the basics of software development until we demonstrated otherwise. Some trainers were better than others of course, but in general they were efficient and useful.

A question which I like to use when interviewing C++ programmers: what is the range of a 32-bit
integer?

I don’t use this question very often anymore, or at least I don’t let it influence my decision very
much (which is why I don’t mind spilling the beans here), because the correlation with other
technical skills turns out to be not as strong as I thought it would be. Still, there are some
interesting patterns in the kind of people who know the answer versus those who do not.

Among the people who do not know the answer, some of them react quite affronted that they would even
be expected to. What is the point, they will ask, in having memorized some little piece of trivia
which they could Google up in a few seconds? Isn’t “knowing where to find it” a much more useful
skill? Ask me about architecture! Ask me about design patterns and data structures! All of these
objections have some validity, and indeed we will certainly ask about those other things during the
interview. Still, I believe that it is perfectly reasonable to expect a good developer to know the
answer to the above question by heart.

One obvious observation that can be made here is that, unless he is very certain that he
will be able to evade justice for the remainder of his life, this was a pretty stupid thing to do:
the punishment for escaping from prison is likely to be a lot harsher than the 21 months in
minimum-security he received for his original crime.

Another question that came up in the /. comments is whether 21 months in minimum-security prison is
an appropriate punishment for a spammer. Many people made the point that, although obnoxious,
spamming is a non-violent crime and should therefore be treated less seriously than, say, murder.

With my subscription to XS4ALL, I received a Thomson Speedtouch 716 ADSL/Wifi router, currently
running software release 6.1.9.6. Behind that router, I have a Linux server which serves as the
webserver for the blog you’re reading right now, as well as my mailserver and a few other things.
The Linux server also acts as a firewall for the rest of my network:

As you can see, the ADSL router and anything connected to it through the WiFi is considered
untrusted: the real access point to my internal network is the Linux machine.

Among other things, the Speedtouch has the ability to support Voice-Over-IP by attaching an analog
phone. Unfortunately, this functionality does not work in combination with the “assign public IP to
a machine on the local network” setting. Which is a pity, because behind the router is my Linux
server, running a web- and mailserver among other things, and I really want that server to have my
public IP address. Partly because having the server NATted could cause problems with mail, in
particular, in the sense that when I send out mail to another server, some suspicious spamblocker
software may take offense if the address reported in the headers of my outgoing mail does not match
my actual IP. But mostly because having a web/mail/FTP/whatever server hidden behind a NAT, just
feels wrong.

The jump was a birthday present for my father, who has always been very interested in everything
related to planes. But of course, when we gave him the gift certificate, it went without saying that
me and my brother would jump as well.

A week or two ago, the ancient laptop I use as my personal web/mail/fileserver and firewall,
suddenly got a bit flaky: it kept running, but all attempts to write to the disk failed. Naturally,
this prompted me to get extra conscientious about making sure everything of importance was backed up
regularly (my e-mail was already being backed up automatically each day, but I discovered that the
MySQL database containing my Wordpress articles was not in the backup set — oops). A reboot fixed
the problem, however, so I didn’t run out and get a replacement drive just yet.

However, last Thursday the same thing happened again, and this time after a reboot all I got was the
message “primary hard disk not found”. So that’s why my server was unreachable for the past couple
of days. It’s quite possible that I lost some mail, too — I have a fallback mailserver through my
DNS provider, but I’m not sure that they will have retained everything for three days. If
you sent me an e-mail recently and have not received a response yet, please send it again.

This post is not going to contain any original insights into the spam problem, but I need to vent a
bit. And, as the title suggests, apparently the news still hasn’t reached all the people it needs to
reach, so maybe it won’t hurt to repeat it again.

So yesterday, as happens every couple of months, a spammer somewhere in Pakistan decided to randomly
pick the mwolf.net domain as the fake ‘from’ address for his various unsavoury commercial offerings.
Which means, of course, that I get a few hundred bounces from well-meaning but naive mailservers,
configured by well-meaning but naive admins.

Hi all,
I have reason to believe that some of my mail from my mwolf.net account is not reaching the intended
recipients. If you sent me an e-mail recently and did not get a response from me, it may be that I
sent one but it didn’t arrive. If this is the case, please re-send your message and I will try to
reach you though some other way. Alternatively, you can leave a comment on this post. Sorry for the
inconvenience.

And yes, I am aware that I have not posted anything new on this blog for the past half year or so..

In response to my article about using the recent
IPTables module to fight brute-force password attacks, based on an idea from Andrew Pollock, a reader worked out the
idea into a complete firewall script, with configurable whitelisting, the ability to block multiple
ports, and several other enhancements. Read his post for the details.

You can download his firewall script here. You can contact the author at the address
meetscott at the domain netscape.net.